# The 35th International Symposium on Lattice Field Theory

18-24 June 2017
Palacio de Congresos
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# Poster Session

## Place

Location: Palacio de Congresos
Date: 20 Jun 19:30 - 21:30

## Contribution List

Displaying 36 contributions out of 36
Type: Poster Session: Poster Session
We summarize previous work on $\bar b \bar b u d$ four-quark systems in the Born-Oppenheimer approximation and discuss first steps towards an extension to the theoretically more challenging $b \bar b u \bar d$ system. Strategies to identify a possibly existing $b \bar b u \bar d$ bound state are discussed und first numerical results are presented.
Presented by Ms. Antje PETERS on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
Several important observables, like the quark condensate and the Taylor coefficients of the QCD pressure with respect to the chemical potential, are based on the trace of the inverse Dirac operator or its powers. Such traces are traditionally estimated with "noise vectors". We explore alternative approaches based on polynomial approximations of the inverse Dirac operator.
Presented by Mr. Philippe DE FORCRAND on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
We describe our experiences porting the Regensburg implementation of the DD-$\alpha$AMG solver from the first-generation Intel Xeon Phi processor (Knights Corner) to its successor (Knights Landing). We present the performance of the code on a single processor as well as the scaling behavior on many nodes of QPACE 3, which utilizes Intel's new Omni-Path fabric.
Presented by Mr. Daniel RICHTMANN on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
We present an update of BQCD, our Hybrid-Monte-Carlo program for simulating lattice QCD. BQCD is one of the main production codes of the QCDSF collaboration and is used by CSSM and in some Japanese finite temperature and finite density projects. Since the first publication of the code at Lattice 2010 the program has been extended in various ways. New features of the code include: dynamical ... More
Presented by Hinnerk STÜBEN on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
The QUDA library for Lattice QCD on NVIDIA GPUs will be around for 10 years in 2018. In this time QUDA has developed from an acceleration library for solvers to a framework for developing QCD simulations. It support many different fermion discretizations, and features many algorithms like Adaptive Multigrid, deflation and Block Krylov space methods, using various techniques such as mixed-precision ... More
Presented by Dr. Mathias WAGNER on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
We present preliminary simulation results of the lattice sine-Gordon model which show evidence of the Berezinskii-Kosterlitz-Thouless phase transition. Our simulation algorithm uses Fourier accelerated hybrid Monte Carlo techniques to reduce autocorrelations. The BKT transition involves a topological phase, with no local order parameter, driven by the physics of topological defects. The sine-Gord ... More
Presented by Prof. Joel GIEDT on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
The one-dimensional extended t-V model on a lattice describes fermions with repulsive interactions of finite range and exhibits a quantum phase transition between a Luttinger liquid conducting phase and a Mott insulating phase. Its properties make it useful in the description of candidate materials for Mott transistor devices. It is known that by tailoring the potential energy of the insulating sy ... More
Presented by Dr. Marcin SZYNISZEWSKI on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
Lattice simulation of charmonium resonances with non-zero momentum provides additional information on the relevant two-meson scattering matrices. However, the reduced rotational symmetry in a moving frame renders a number of states with different J^P in the same lattice irreducible representation. The identification of the underlying spin and parity for these states is particularly important fo ... More
Presented by Prof. Sasa PRELOVSEK on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
We present colour field density profiles for some of the first SU(3) gluonic excitations of the flux tube in the presence of a static quark-antiquark pair. The results are obtained from a large set of gluonic operators.
Presented by Pedro BICUDO on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
Parton distribution functions provide an important insight into the inner structure of hadrons, by giving information on the momentum and spin distribution of partons. Extracting parton distribution functions (PDFs) directly from Lattice QCD has been thought impossible, since they are given in terms of non-local light cone correlations in Minkowski space-time and light-like distances are not acce ... More
Presented by Ms. Aurora SCAPELLATO on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
Track: Nonzero Temperature and Density
We calculate the entropy of SU(3) Yang-Mills theory in a moving frame using the Symanzik improved action. By using shifted boundary conditions a moving frame can be realized on the lattice. In this setting the momentum density and the renormalization constant of the offdiagonal elements of the energy-momentum tensor are computed. The results are then used to compute the entropy density.
Presented by Mr. Dominik LAUBACH on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
We present updated results of the infrared behavior of the SU(2) model with 6 and 8 fundamental representation fermions. We use the gradient flow method with the Schrödinger functional boundary conditions to measure the running of the coupling in these theories and find fixed points on both. We also measure the mass anomalous dimension from these configurations and compare those results to mass a ... More
Presented by Mr. Viljami LEINO on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
We report on continued studies of the non-perturbative beta function in SU(3) gauge theory with 12 fundamental massless flavors, a model which remains controversial as to the existence of an infrared fixed point. We extend our previous work (Phys. Rev. D94 (2016) no.9, 091501) to stronger gauge couplings and test conformality for this model.
Presented by Prof. Zoltan FODOR on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
Track: Algorithms and Machines
In lattice QCD simulations the formulation of the theory in lattice should be chiral in order that symmetry breaking happens dynamically from interactions. In order to guarantee this symmetry on the lattice one uses overlap and domain wall fermions. On the other hand high computational cost of lattice QCD simulations with overlap or domain wall fermions remains a major obstacle of research in the ... More
Presented by Dr. Rudina OSMANAJ (ZEQIRLLARI) on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
In the landscape of approaches toward the simulation of Lattice Models with complex action the Complex Langevin Equation (CLE) appears as a straightforward method with a simple, well defined set up. Its applicability, however, is controlled by certain specific conditions which are not always satisfied, such as holomorphy and limited diffusion in the non-compact directions. We here provide some det ... More
Presented by Dr. Erhard SEILER on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
In the calculation of quark condensates using staggered fermions, the contribution induced by the zero modes of the Dirac operator behaves as a simple pole as approaching to the chiral limit. We use Lanczos algorithm to find the would-be zero modes of the staggered Dirac operator and identify their quantum numbers by the spectral flow method. We plan to apply this method to the calculation of quar ... More
Presented by Mr. Hwancheol JEONG on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
It is necessary to improve flavor-changing currents for calculating $\bar{B}\rightarrow D^{(*)}\ell\bar{\nu}$ semi-leptonic form factors using Oktay-Kronfeld (OK) heavy-quarks. The OK action reduces the heavy-quark discretization effect up to $\mathcal{O}(\lambda^3)$ in the HQET power counting. To get a full advantage of the OK action, we need to improve the currents up to the same level as well. ... More
Presented by Mr. JAEHOON LEEM on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
We compute the hadronic tensor $W_{\mu\nu}$ in the Euclidean space by calculating 4-point correlation functions on the lattice, two topologically distinct connected insertons are considered which help to separate the connected sea parton contribution from that of the disconnected sea. We try to convert the Euclidean hadronic tensor to Minkowski space through inverse Laplace transform. As an explor ... More
Presented by Prof. Liu KEH-FEI on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
The nature of resonances and excited states near decay thresholds is encoded in phase shifts, which can be extracted from single-particle and multiparticle correlators in finite volumes. Lattice calculations have only recently reached the required precision for a reliable study of such correlators. The distillation method has been a significative improvement insofar as it simplifies quark contract ... More
Presented by Mr. Simon WEISHÄUPL on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
I present a multi-grid Lanczos algorithm that reduces the memory requirements both on disk and in working memory by one order of magnitude for RBC/UKQCD's 48I and 64I ensembles at the physical pion mass. The precision of the resulting eigenvectors is on par with exact deflation.
Presented by Christoph LEHNER on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
N=1 supersymmetric Yang-Mills theory describes interacting gauge fields and their superpartners, the spin 1/2 gluinos. A gluino mass term breaks supersymmetry softly. In the supersymmetric limit, the physical particles are expected to form supermultiplets. In our numerical simulations with gauge groups SU(2) and SU(3) we obtained results for the masses of the lowest lying bound states and som ... More
Presented by Prof. Gernot MÜNSTER on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
I will provide an update on HPQCD second-generation B-physics calculations using improved NRQCD b quarks and HISQ light quarks on the MILC n_f=2+1+1 gauge configurations. The configurations include the effect of HISQ sea quarks with a range of light quark masses going down to the physical point for a range of lattice spacing values. Results include B and Bs mixing matrix elements and tests of ... More
Presented by Prof. Christine DAVIES on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
The use of deflation is a common technique to speed up the calculation of quark propagators for Wilson/clover or domain wall fermions. I report on numerical experiments using deflation to compute quark propagators for the HISQ improved staggered action. The method is tested on HISQ gauge configurations, generated by the MILC collaboration, with lattice spacings of 0.15 fm, with a range of volumes ... More
Presented by Dr. Craig MCNEILE on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
Track: Theoretical Developments
Common lore suggests that no well-defined order parameters exist in $N$-color QCD with massive quarks which are non-trivial at zero baryon density. However, such order parameters do exist when there are $n_f$ quark flavors with a common mass and $d\equiv{\rm gcd}(n_f,N) > 1$. Such theories have $Z_d$ color-flavor center symmetry arising from intertwined color center transformations and cyclic flav ... More
Presented by Mr. Aleksey CHERMAN on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
The framework of shifted boundary conditions has proven to be a very powerful tool for the study of thermal quantum field theories. For instance, it has been considered for the determination of the equation of state of the Yang-Mills theory with high accuracy. The set-up of shifted boundary conditions can be generalized to QCD and it is expected to lead to a similar breakthrough. We present result ... More
Presented by Dr. Mattia DALLA BRIDA on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
We perform a pilot study of the perturbative renormalization of a Supersymmetric gauge theory with matter fields on the lattice. As a specific example, we consider Supersymmetric N =1 QCD (SQCD). We study the self-energies of all particles which appear in this theory, as well as the renormalization of the coupling constant. To this end we compute, perturbatively to one-loop, the relevant two-point ... More
Presented by Dr. Marios COSTA on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
Track: Standard Model Parameters and Renormalization
We investigate the SU(3) Yang Mills theory at small gradient flow time and at short distances. Lattice spacings down to a=0.015fm are simulated with open boundary conditions to allow topology to flow in and out. We study the behavior of the action density E(t) close to the boundaries, the feasibility of the small flow time expansion and the extraction of the $\Lambda$-parameter from the stati ... More
Presented by Mr. Rainer SOMMER on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
We study the scaling of observables computed with an $N_f=2+1+1$ fully-twisted tmQCD valence action on $N_f=2+1$ CLS ensembles. Particular attention is given to relative cutoff effects in basic quantities such as quark and meson masses and decay constants, as well as to isospin splitting of pseudoscalar mesons.
Presented by Mr. Javier UGARRIO MUÑOZ on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
In this work we present the perturbative computation of the difference between the renormalization factors of flavor singlet and nonsinglet bilinear quark operators (scalar, pseudoscalar, vector, axial vector and tensor) on the lattice. Nonperturbative estimates of the renormalization factors for the singlet operators are notoriously difficult to obtain via numerical simulations, due to the presen ... More
Presented by Mr. Gregoris SPANOUDES on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
The symmetric momentum subtraction scheme (SMOM) has been introduced to overcome exceptional momentum flows. However, it is quite restrictive to the momentum choice - the momentum squared of all legs are identical. Therefore, a generalization called interpolating momentum subtraction scheme (IMOM) has been developed, where a free parameter $\omega$ allows for more freedom in the momentum assi ... More
Presented by Dr. Holger PERLT on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
Unlike the simple picture shown by the quark model, the origin of the proton mass based on the related experiments results are pretty complicated and challenge our understanding of the QCD physics at the non-perturbative region. I should show our recent lattice QCD results on the decomposition of the proton mass and how important the gluon components are.
Presented by Prof. Keh-Fei LIU on 20/6/2017 at 17:30
Type: Poster Session: Poster Session
We study the gaps between thermodynamic quantities in the hot and cold phases of the SU(3) gauge theory at the first order phase transition point. Performing simulations on lattices with various spatial volume and lattice spacing, we calculate the energy gap (latent heat) by a method using the Yang-Mills gradient flow and compare it with that by the conventional derivative method.
Presented by Dr. Shinji EJIRI on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
One of the historical suggestions to tackle the strong CP problem is to take the up quark mass to zero while keeping $m_d$ finite. The $\theta$ angle is then supposed to become irrelevant, i.e. the topological susceptibility vanishes. However, the definition of the quark mass is scheme-dependent and identifying the $m_u=0$ point is not trivial, in particular with Wilson-like fermions. More specifi ... More
Presented by Dr. Julien FRISON on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
We present an exploratory study of leading isospin breaking effects in mesonic masses using $O(a)$ improved Wilson fermions. Isospin symmetry is explicitly broken by distinct masses and electric charges of the up and down quarks. In order to be able to make use of existing isosymmetric QCD gauge ensembles we apply reweighting techniques. The path integral describing QCD+QED is expanded perturbativ ... More
Presented by Andreas RISCH on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
We present recent results of the indirect CP violation parameter in the neutral kaon system, $\varepsilon_K$ calculated using lattice QCD inputs including $\hat{B}_K$, $\xi_0$, $\xi_2$, $V_{us}$, $V_{cb}$, and $m_c(m_c)$.
Presented by Prof. Weonjong LEE on 20/6/2017 at 18:30
Type: Poster Session: Poster Session
In this work we present an extension of the Lüscher formalism to include the interaction of particles with spin, focusing on the scattering of two vector particles. The derived formalism will be applied to Scalar QED in the Higgs Phase, where the U(1) gauge boson acquires mass.
Presented by Mr. Fernando ROMERO-LOPEZ on 20/6/2017 at 17:30